1. Field of the Invention
The present invention relates to tie beams and girders comprising a core section and a facing intended for facade walls constructed from prefabricated parts and consisting of at least two tie beams or girder sections which are displaceable with respect to each other and which are covered on all sides with steel plate facing.
2. Description of the Prior Art
In the case of known tie beams and girders of this type--which are also known as stay beams or horizontal sections--it is common practice to use a supporting steel core piece covered with aluminum sheeting or the like. In practice, it is not possible to construct a steel core section of this type in such a way that panels, panes of glass and the like can be mounted directly on the steel core section by simply attaching a retaining strip and interposing packing elements, as a piece having the requisite preformed elements incorporated therein for receiving and supporting packing elements cannot be produced from steel, at least, in an economically viable manner. It is also difficult to produce multipart steel core pieces for tie beams and girders which are capable of absorbing horizontal or vertical compensating movements of the facade.
The requirements which must be satisfied by structural parts, particularly in multi-storey construction, are becoming increasingly stringent. For example, for load-bearing components such as tie beams and girders, the fire resistance class F90 according to DIN 4102 is applicable. In other words, fire-resisting tie beams and girders must be employed. This means that when one side of the structural part is exposed to the influence of a temperature of 1000.degree. C. for a period of at least 90 minutes, the temperature on the other side of the material should not be more than 140.degree. above its initial temperature and at none of the measuring points should it be more than 180.degree. above its initial temperature. In the case of panes of glass for a facade, a glass is currently being developed which will provide for an F30 fire-resistance class, and possibly an even higher class according to DIN 4102, for the glass elements per se. This means that even the glass elements are fire-resisting, i.e., fire-retardant, for a period of 30 minutes, whereas these elements were previously only considered to be fire-resisting for a period of at least 3 minutes.
The increasingly stringent fire resistance requirements placed on tie beams and girders could only previously be met by tie beams and girders comprising steel core pieces. However, a steel core piece cannot be used for facades which are to be produced in an economical and reliable manner for the reasons indicated above. An aluminum core piece which will enable the cross-section of this core piece to be constructed in a simple and economical manner in the desired and necessary form for panels, panes of glass and the like to be mounted directly thereon can only be used if special measures are adopted to comply with the fire resistance requirements for tie beams and girders.